T2 Star weighted MR angiography (SWAN) showed microbleeds in the left white matter, indicating endothelial damage and blood brain barrier disruption. Perfusion-MRI showed no area of decreased CBF.

After procedure,peri-aneurysmal edema gradually remissions　　　

Purpose : Post embolization high intensity signal areas in FLAIR MRI images (HISA) are infrequent. Pathogenesis of HISA that appeared following endovascular treatment was poorly understood. In this presentation,we demonstrated 6 cases of cerebral lesion after coil embolization, and the mechanism of lesion appearance was discussed.

Case １　　　　 74 y.o. 　　Female 　　　　　　　

Case3 　　 58 y.o. 　　　Female 　　　　　　

Case2 　　 78 y.o. 　　Female 　　　　　　　

Lesion 　：　 Lt.IC-PC. AN. neck/dome/depth(mm) 　： 8.21/12.62/14.38Unrupture

Procedure ： Balloon AssistContrast agent 　：　 Iohexol 223ml 　VER 　：　 27.7% 　 neck remnantBioactive coil 　：　 used（ unlabel and coil maigration to parent artery ）

頭部 MRI ：白質病変やや軽減

Lesion 　：　 A com. AN. neck/dome/depth(mm) 　： unknownUnrupture

Lesion 　：　 Lt.BA-SCA AN. neck/dome/depth(mm) 　： 7.07/7.77/9.81Rupture → SAH Hunt and Hess 2/Fisher 4

Procedure ： unknownContrast agent 　：　 unknown 　VER 　：　 unknown 　 neck remnantBioactive coil 　：　 unknown

POD1264 re-embolization

Procedure ： single catheter

Bioactive coil 　：　 none

Procedure ： single catheterContrast agent 　：　 Iohexol 143ml 　VER 　：　 28.4% 　　　　 neck remnantBioactive coil 　：　 none

POD391 re-embolization

Procedure ： Balloon Assist

Bioactive coil 　：　 used

B-MRI ： peri-aneurysmal edema was found, and exacerbated gradually.　　

B-MRI ： coil compaction and

peri-aneurysmal edema are found.

The edema was exacerbated gradually

B-MRI ： coil compaction, peri-

aneurysmal edema, and

brainstem compression are

found. POD385POD6 POD566

POD1206 POD1889

POD7 POD92 POD329 POD536

１． Department of Endovascular Neurosurgery ＠ International Medical Center,Saitama Medical University 　　　　２． Department of Neurology @ Nara City Hospital

ASNR 2015EP-99

High Intensity Signal Areas in FLAIR MRI (HISA) 　 after Coil Embolization to Cerebral Aneurysms: Case series

Yoshiaki Kakehi, Eisuke Tukagoshi, Jun Niimi, Hiroaki Neki, Nahoko Uemiya, Koji Mizogami, Shinya Kohyama , Fumitaka Yamane, Shoichiro Ishihara

Conclusions : The mechanisms of HISAs after coil embolization were unknown, the adverse inflammatory reactions were proposed. Some of these cases seem to be curable in use of steroid, we should take care of not only to the appearance of neurologic deficits but HISA in brain parenchyma.

Case4 　　 58 y.o. 　 Female 　　　　　　　

Lesion 　：　 Lt.IC-Oph A. AN. neck/dome/depth(mm) 　： 5.33/7.28/5.49UnruptureProcedure ： Balloon AssistContrast agent ：Iohexol 316ml 　VER 　：　 21.9% 　 Complete obliterationBioactive coil 　：　 none

On POD39, higher brain dysfunction was developed. MMSE 25/30. The cerebrospinal fluid exhibited a protein level at 46 mg/dL.

・ The mechanism of blood brain barrier disruption could be explained with contrast agents causing endothelial cell shrinkage and opening of tight junctions. In the territory of the artery disrupted blood brain barrier, white matter exposure to allergen. At that time, we think T-cell activation is induced, and allergens of each cases induced an ADEM-like reaction with a T cell–mediated autoimmune process. The CSF results lend further credence to this hypothesis. ・ The unilateral involvement could be explained by the fact that the BBB disruption was limited to areas of higher and more intense contact with contrast agents.・ In case4, platinum or Iohexol are predicted as allergen. And in case5, nickel, involved the stent used for coil embolization assist, is predicted as allergen by patch testing, not platinum, because this symptom was’nt found at post coil embolisation to Lt. VA dissection with SAH.

Postoperative CT:

Case6 　　 63 y.o. 　 Female 　　　　　　Lesion 　：　 Rt.IC-PC. AN. neck/dome/depth(mm) 　： 3.31/11.9/13.1Unrupture

Procedure ： Double CatheterContrast agent ： Iohexol 57ml 　VER 　：　 43.4% 　 complete obliterationBioactive coil 　：　 none

Although there were no symptoms,f/u MRI showed multiple lesions in the white matter and occipital cortex in the territory of the right middle cerebral artery (MCA). Perfusion-MRI showed decreased CBF within the lesions.

POD239 re-embolization

Procedure ： Balloon

Assist

Bioactive coil 　：　 used

Discussion of pathology in case4 and 5 ADEM-LIKE REACTION ANEURYSM COILING Leonardo et al. Neurosurgery 66:, 2010

Discussion of pathology in case6 Delayed thrombus formation due to a coil loop migration into the parent artery

Discussion of pathology in case1, case2, and case3 Postembolization perianeurysmal edema

・ Although mimicking case 4 and 5, rt. parietal cortex was involved in HISA in FWI. Besides, P-MRI showed decrease in cerebral blood flow at the lesion, and the protein in cerebrospinal fluid was normal, different from case4 and 5. ・ We think the HISA in this case is due to thrombus with small coil loop migration into the parent artery.

POD39 POD58 POD90

Extravasation of contrast agent was found,indicating blood brain barrier disruption.

Post operative CT didn’t show extravasation of contrast agent and edema of cortex.

POD132 POD140POD253

Case5 　　 39 y.o. 　 Female 　　　　　　　

Lesion 　：　 Rt.IC-dorsal. AN. neck/dome/depth(mm) 　： 4.8/4.6/3.2 Unrupture

Procedure ： Stent AssistContrast agent： Iopamidol 50ml 　VER 　：　 23.9% 　 Body fillingBioactive coil 　：　 none

Postoperative CT:

Edema of right cortex was found, not entirely Blood Brain Barrier disruption.

POD27 POD38 POD45

POD1630

After procedure,peri-aneurysmal edema gradually remissions　　

After procedure,peri-aneurysmal edema remissions transiently, but coil compaction and aneurysm expansion were found gradually, and peri-aneurysmal edema was exacerbated.

MRI showed multiple lesions in the left white matter were found.

We have no COI with regard to our presentation.

After administration of intravenous methyl-prednisolone at a dose of 1,000 mg/day for 3 days, the symptoms were almost completely resolved. MRI showed a reduction in the size of the lesions.Perfusion-MRI showed no areas of decreased CBF.

On POD27, the patient got an epileptic seizure. MRI showed multiple lesions in the left white matter.The cerebrospinal fluid exhibited a protein level at 58 mg/dL.

After administration of intravenous methyl-prednisolone at a dose of 1,000 mg/day for 3 days/weeks, for 3weeks, MRI demonstrated almost complete resolution.

The cerebrospinal fluid exhibited a normal protein level.

Followed closely without treatment, the leisons gradually remissions.

small coil loop migration into the parent artery.

Past Hitory : At 37 y.o.SAH with left vertebral artery dissection, performed parent artery embolization.

Refferences Kyriakos, et al. Neurology 84.1 (2015): 97-99. Horie, Nobutaka, et al. Journal of neurosurgery 106.5 (2007): 916-920. DEUS-SILVA, Leonardo, et al. Neurosurgery, 2010, 66.1: E222-E223.

Cohen, José E., et al. Journal of Clinical Neuroscience 19.3 (2012): 474-476. Craven, I., et al. AJNR 30.10 (2009): 1998-2000.

・ The development of postembolization perianeurysmal edema has been reported infrequently. ・ The edema is likely to develop around partially thrombosed aneurysms as well as large or giant aneurysms. In our cases, case1 and 2 were large aneurysm, and case 3 is partially thrombosed aneurysms.・ A significant proportion of patients who develop postembolization perianeurysmal edema are most likely asymptomatic, as well as our 3 cases.・ Pulsatile blood flow, hemorrhaging within the aneurysm wall, the inflammatory process, and endothelial growth factor in the aneurysm wall have also been proposed as factors that may play a role in the development of such edema. Especially, the pulsatile blood flow when striking the coils may result in a regrowth of the aneurysm and may also be transmitted to the aneurysm wall via the coils, thus leading to the perianeurysmal edema. It is reported that perianeurysmal edema is associated with aneurysm recanalization and regrowth. In our all 3 cases, coil compaction was found. In case1, and 2 , aneurysm recanalization was found, and in case3, aneurysm regrowth was found,too.・ Treatment options for perianeurysmal edema may include conservative management in asymptomatic patients, the use of steroids and other anti-edematous medications in symptomatic patients. Because the edema is associated with recanalization and regrowth, further embolization or neck clipping were performed frequently. In our cases, we performed re-embolization. In case 1,and 2, after procedure, MRI showed remission of perianeurysmal edema, but in case 3, remission was transient.